Isolation of polyvinyl chloride degrading bacterial strains from environmental samples using enrichment culture technique

Abstract

Plastic causes serious damage to the environment, both during its production and disposal. Biodegradation of plastic waste using microbial strain could offer a solution to the problem. Microorganisms have been a good resource for solution to this problem due to their diverse metabolic capability, adaptability to different environment and possibility of isolation using artificial growth media for utilization in situ. In the present investigation, potent microbial strains degrading plastic constituting polymer polyvinyl chloride (PVC) were isolated using enrichment culture technique. To increase the chances of isolating such strain which could have adapted to metabolize plastic constituting polymers, samples were collected from different environmental sites that were rich in plastic waste. These samples were used as a source of microbial culture for enrichment of potential PVC degraders. After then, some bacterial species were subsequently isolated on solid agar medium containing emulsified PVC polymer. The strain PVC 4 characterized as Micrococcus species was found to be more efficient among the other isolates and was chosen for further studies. The biodegradability of PVC by Micrococcus species with PVC as a sole carbon source was determined by their ability to release chloride from PVC polymer, increase their cell density in test media, carbon dioxide production and growth on the surface of PVC film in plate assay. The Micrococcus species showed 0.36% release of chloride and 8.87% mineralization measured in terms of carbon dioxide evolution respectively over a period of 70 days in PVC containing media. The increase in cell density in liquid growth media constituting PVC polymer as a sole source of carbon and growth of cells on the surface of PVC film further substantiate the potential of isolated strain for PVC utilization.

Keywords: Polyvinyl chloride, biodegradation, Micrococcus species, enrichment culture